What Causes Limbs Joint Pains, Sore Throat And Mouth Ulcers?

Since July I have been having severe joint pains in my limbs, cronic sore throat, mouth ulcers, to the point that I can hardly walk ot use my hands at times. I have had lots of bllod tests that were negative including Lymes Disease, and so have been told it is a Virus. Do Virus's go on for this long. I am normally very fit nd healthy and would like my life back.